12 ms·

Does the Past Still Exist?

177 points by nsoonhui 4y ago

echelon 4y ago
If somehow humans or human ancestors (AGI?) endure to the point they can bend the laws of physics and play back the light cone, I wonder if they'll be interested in revisiting all of us to learn about the past. To see and touch the dinosaurs, visit Einstein, see everything, even our thoughts. An undetectable time machine that might surround us even now. A traversable field of time. A kind of high fidelity afterlife. (I am clearly not a physicist.)
- cercatrova 4y ago
  The show Devs actually explores this concept. It's by the director of Ex Machina.
  - colordrops 4y ago
    Also Interstellar.
  - mdrzn 4y ago
    It was such a good show, with an interesting POV. Wish they would do a 2nd season.
- xwdv 4y ago
  Personally, I think perhaps we are the machine, right now. Everything that has happened now has already happened, and we’re just reliving it. Who knows what iteration of the loop we might be on right now. Perhaps on our first run free will was much more obvious and abundant, in ways that we simply can’t even imagine right now, kind of like trying to imagine light when you’re born blind. However, the end result still ends up being exactly what you experience now, minus the running dialog of free will. Our body is controlled by our mind, and our mind is controlled by our consciousness, which is capable of observing and altering our mind’s thoughts. But as far as I can tell, we don’t seem to have any mechanism for “observing” our consciousness. That is the missing freewill component, which may have only existed in our first run.
  - colordrops 4y ago
    I suspect being able to directly observe consciousness will involve transcending the individual self and end up solving the problem of free will, in that there is no single self to have free will, i.e. consciousness is not tied or confined to any single individual.
    - xwdv 4y ago
      So everything we experience now on an individual level is just the result of that unified consciousness’s choices?
      - colordrops 4y ago
        Assuming that our individual oerception of experience and agency applies analogously to this greater consciousness, then I suppose so, but I don't know if our narrow minds can comprehend or express the way it operates.
  - dsego 4y ago
    Simulation theory by Philip K Dick https://youtu.be/bbW6ZOmoFgY https://youtu.be/bbW6ZOmoFgY
  - rytill 4y ago
    > But as far as I can tell, we don’t seem to have any mechanism for “observing” our consciousness. That is the missing freewill component, which may have only existed in our first run. Do you think the "first run" version of yourself would have made your HN comment?
    - xwdv 4y ago
      I think somehow the free will of my first run’s version must have willed my consciousness to think about this thought and come to this conclusion.
- LeoPanthera 4y ago
  Stephen Hawking's time traveller party: https://youtu.be/elah3i_WiFI https://youtu.be/elah3i_WiFI (The invitations were posted after the party had concluded.)
  - Geee 4y ago
    Why would anyone show up if they knew that no one will show up?
- dalmo3 4y ago
  > If somehow humans or human ancestors You probably meant descendants, but that just made your comment delightfully coherent.
thunkle 4y ago
- mgdlbp 4y ago
  https://en.wikipedia.org/wiki/Information-theoretic_death https://en.wikipedia.org/wiki/Information-theoretic_death ?
  - thunkle 4y ago
    Yeah, exactly. How did you come about this?
    - mgdlbp 4y ago
      Not sure; it's not in my notes. I want to say an HN comment, but I don't recognize any of the few that include the link. -- Edit: The browser history still exists, although I cannot disprove that it was created Last Thursday; 'twas the comment near the bottom of this thread that intrigued me with its sole content, that link: https://news.ycombinator.com/item?id=1755748 https://news.ycombinator.com/item?id=1755748
- Atiscant 4y ago
  If you care about the question more than from a purely curiosity standpoint, there is a difference tween “flesh” and “body” in (at least some) of Christianity. The “Lord of Spirits” (an orthodox podcast) has done an in-depth discussion on both the body of God and the bodies of humans, angels and demons. Just as an example, when Adam and Eve was expelled from the garden they were covered in “garments of flesh/skin” depending on the translation. I do not want to start a discussion on Christianity, just to point to that there is a more subtle understanding in the church whether or not you believe in it.
  - FrozenVoid 4y ago
    Body could be 'subtle' astral/etheric matter. Flesh is strictly physical biological matter.
Borrible 4y ago
To answer this question one needs True Detectives. https://www.youtube.com/watch?v=9oX2xFo7JA4 https://www.youtube.com/watch?v=9oX2xFo7JA4 But, ist the other side of the block-universe existing? Is it growing in that direction? Are you on the edge of that growth? Or are you already ghosts of the past talking among themselves? Again. And again. Forever.
dandanua 4y ago
Reminded me of https://twitter.com/DarthPutinKGB/status/1549655121000366080 https://twitter.com/DarthPutinKGB/status/1549655121000366080 "The hard part about doing propaganda is that the past changes so quickly you have no idea what will happen yesterday"
- spratzt 4y ago
  This is a variation on an old joke. Q: What is the hardest task for a Marxist historian? A: To forecast the past.
pdonis 4y ago
The article does not even discuss the obvious alternative that is perfectly consistent with relativity: all events in your past light cone "exist" (a better term would be "are fixed and certain"). This avoids all of the issues mentioned in the article while not committing you to the "existence" of anything that might not be fixed and certain based on the information you have at any particular time. What always amazes me about discussions like this is how even physicists who are experts in relativity fail to see the obvious implications of the fact that, in relativity, spacetime is divided into three regions instead of two. Instead of just "past" and "future", there are "past light cone", "future light cone", and "spacelike separated". "Past light cone" and "future light cone" behave more or less like our intuitive concepts of "past" and "future"--the past light cone is what is fixed and certain and can't be changed, and the future light cone is what can possibly be changed based on things we do here and now. But the spacelike separated region is not like anything in our intuitions, since it is not fixed and certain as far as we know here and now, but we also can't do anything here and now to change it. But instead of recognizing all this and considering its implications, discussions like this article talk as if the only way to divide spacetime up into regions is "past" and "future" separated by a "now" slice (and the "now" slice is of course frame-dependent so it can't have any physical meaning), or to talk as if the only thing that "exists" is the single point in spacetime that is our "here and now". It's disappointing.
- panda-giddiness 4y ago
  The author hasn't neglected to consider light cones – she literally describes them in her post, as evinced by her mentioning 45 deg lines on a spacetime diagram, causally connected/disconnected events, etc. Of course you have described a perfectly good way of thinking about the past/future (and to your credit, she surely should've included what you described). But in her defense, what you have described is also the most obvious explanation consistent with special relativity – the "past" and "future" outside one's line cone cannot be objectively defined, as you could always (hypothetically) boost to another frame in which the disconnected past becomes the disconnected future (and vice versa). Undoubtedly the author is aware of this fact, so I assume the purpose of this blog post was simply to motivate other hypotheses about the nature of time.
bni 4y ago
My favorite Sci-Fi about this: https://www.goodreads.com/book/show/823062.The_Light_of_Other_Days https://www.goodreads.com/book/show/823062.The_Light_of_Othe...
Brajeshwar 4y ago
OffTopic but curious (not derogatory): Of late, I feel that her video are deepfake with Sabine Hossenfelder speaking from behind. I subscribe to her YouTube channel and I'm a regular. What am I missing?
- djmips 4y ago
  I can see why you think that but I don't think it's quite so elaborate. More likely just production changes, maybe filters.
- rubslopes 4y ago
  It's the first time I've seen a video of her and I had the same impression. I think it has something to do with her lack of arm movement (also not derogatory).
- ubercore 4y ago
  There's a smoothing filter on that video that makes it look a bit fake.
- rapjr9 4y ago
  She uses green screen a lot to add all the graphics behind and to the sides, which often makes the edge of the person a little random (pixels blink on and off), and the shadows in the graphics may not fall in the same direction as the shadows created by the light on her. In a similar way weather on the news makes the weather person look a bit surreal.
bowsamic 4y ago
Interesting article. Not entirely relevant, but I think that the Buddhist view of time is interesting, and I guess quite relevant to this block universe idea. In the Buddhist view, all things are "emptiness", shunyata, without self-existence. This means that there is no fundamental basis with which you can distinguish between things. For example, there is no fundamental property that you can use to distinguish between you and I, or an apple and a keyboard, or even your body and your consciousness. The distinctions are just concepts that we make up and assert that the world fits into it. The Heart sutra says that not only is this true for all the elements that make up our experience, but even also for causal connections such as time. This view of time was most explicitly emphasised by the Soto Zen philosopher Dogen. He called it Uji, which means "time-being". Effectively he said that being equals time, and that really all time is right now: [quote] An ancient buddha said: For the time being stand on top of the highest peak. For the time being proceed along the bottom of the deepest ocean. For the time being three heads and eight arms. For the time being an eight- or sixteen-foot body. For the time being a staff or whisk. For the time being a pillar or lantern. For the time being the sons of Zhang and Li. For the time being the earth and sky. "For the time being" here means time itself is being, and all being is time. A golden sixteen-foot body is time; because it is time, there is the radiant illumination of time. Study it as the twelve hours of the present."Three heads and eight arms" is time; because it is time, it is not separate from the twelve hours of the present. [/quote] (https://www.thezensite.com/ZenTeachings/Dogen_Teachings/Uji_Welch.htm https://www.thezensite.com/ZenTeachings/Dogen_Teachings/Uji_...) The way we understand this as Buddhists, is that we are both at the very beginning and very end of our path, at the same time we are both deluded beings and also perfectly enlightened Buddhas: > Time is not separate from you, and as you are present, time does not go away. As time is not marked by coming and going, the moment you climbed the mountains [walked the Buddhist path] is the time-being right now. So effectively, we believe that all moments are contained in this moment, because there is no fundamental basis by which we can say that any other moment is separated from this moment. Before and after are illusions, they are just ideas that we have right now.
- ncmncm 4y ago
  "between you and me".
djmips 4y ago
I'm more in the emergent time camp. But the point is that it isn't an open and shut case with regard to the block universe.
amriksohata 4y ago
Somewhat related. In the Srimad Bhagvatam Canto 5, a Hindu scripture, it states that the Universe shell (known as the Brahmanda shell) contains all past, present and future events. https://www.facebook.com/VedicCosmology/posts/do-the-past-and-future-exist-a-new-theory-claims-that-time-does-not-move-forward/1608277619480164/ https://www.facebook.com/VedicCosmology/posts/do-the-past-an... https://gauragopala.blogspot.com/2019/02/we-are-deep-inside-larger-universe-made.html?m=0 https://gauragopala.blogspot.com/2019/02/we-are-deep-inside-...
bambax 4y ago
I'm not sure I understand any of this, but I'm trying. Can this be summarized as "for any two points in time, one can always find an observer for whom those two points are simultaneous"?
- dandanua 4y ago
  For any two points in the event space (spacetime), which are causally disconnected (space-like separated, which means one point is not in the light cone of the other), there is always an observer that perceives them simultaneously. There are also observers for which one point precedes the other and vice versa. There are observers that can't see (or cause) one of the points, or both.
  - bambax 4y ago
    Ah, but then it's not especially counterintuitive: causally independent events can happen in any order... The layman's notion of "time" implies causality/irreversibility. Events that have no causal relation between all have their own little timeline, and it's not troubling or surprising to consider that they are simultaneous / that we examine them in a kind of superposition. Or am I saying something stupid? ;-)
    - dandanua 4y ago
      That's right. We've just learned to believe that there is only a past and a future, where the future is caused by the past. In Special Relativity those are just two light cones, but there are always other events. Though, in a flat spacetime they will affect our future, eventually, because we are moving slower than light. In other words, every event is past to some of our future event. The Big Bang is a different story, because the theory says that spacetime is evolving.
fbn79 4y ago
I suggest you the book "Order of time" by Carlo Rovelli. One think I learned by the book is the locality of time. For example imagine one day people living on mars and you wonder what that people doing in this moment. Well is a wrong question. There is no such thing "this moment" in two far placeces
ffwd 4y ago
I feel like I must be missing something but in the part about the relativity of simultaneity [0] I feel like this is more about the relativity of the observers and the limitations of speed of light than it is about the ontology of time itself? The definition of "now" as when the light hits the mirror on each side is a "constructed" now, a false now if you may. It takes the light longer on the right side than the left side because she is moving through space, all that tells me is that there is no way to communicate a "now" between different observers because there can't be instantaneous communication between observers, not that time itself is relative or physical stuff itself doesn't have a constant time? She says in the video that we have to find a way to operationalize how to find a now, to measure it empirically but maybe that's not possible without running a complete simulation after the fact. But to me it seems not surprising that without instantaneous communication there is no way to create a "now" empirically but that doesn't mean it extends to the ontology of physical stuff itself or time itself. There would still be a time in there (you should be able to see it in a simulation?) Also for example, if you use sound instead of light, if I'm far away from a sound source (farther than the speed of sound), and another observer is closer to it, we would not be able to use the sound source as a source "now", because I would hear it later. Is this the same type of situation or different? I feel like I must be missing something fundamental here but I'm sort of going out on a limb so please don't slaughter me :P [0] https://youtu.be/GwzN5YwMzv0?t=542 https://youtu.be/GwzN5YwMzv0?t=542
- platz 4y ago
  Are you not just taking the position that the only things that exist have to be both 1) Now and 2) Here
  - ffwd 4y ago
    I suppose so... Not sure about the second part but for the first part I think that comes from the idea that I don't think we've ever empirically or even subjectively observed the universe in any other state than "now". We've never personally nor in a scientific experiment observed any physical system being in more than one state, and that one state has to by definiton be in the "now" (Unless I am mistaken). So the past and the future states are essentially nowhere to be found in empiricism ? As for the "here" part I am not sure how to respond to that but it sounds right - any observer has to have contact in some direct way (whether with a scientific instrument or not) to the thing physical system he is observing and as such claiming anything about anything indirect or far away is very hard if not impossible so you get the "here".
galgot 4y ago
My favorite theory about Space and time is the one from Don Hoffman. To summarize, space and time are parts of our interface to interact with other conscious agents , just like our senses of smell, vision, sound. But it is just that, an interface, created by millions years of evolution, and does not shows the true nature of reality, which could be completely incomprehensible to us. Like electricity is incomprehensible to a cat, evolution, which is very power thrifty, provided cats just enough effectives ways to survive and reproduce the way cats do. Same for us. this is very summarized, his ideas goes much farther, for him the base of true reality could be consciousness : https://youtu.be/oadgHhdgRkI https://youtu.be/oadgHhdgRkI and https://youtu.be/ds-7sMfJDUw https://youtu.be/ds-7sMfJDUw
- Trasmatta 4y ago
  How does he reconcile space and time being just an interface created by evolution, when evolution itself is a process that only happens because of time?
  - galgot 4y ago
    Well, evolution happening because of time is again how we "understand" it because we have no other ways to. He doesn't say he has the answer to the true nature of time and space, he is a searcher. Check the vids, it is much better explained than I can do :)
adriand 4y ago
I’m not sure who the intended audience of this upcoming book is, but if it is laypeople, I feel as though the level of explanation is too advanced. Eg: > Just like a ball doesn’t change if you rotate one direction of space into another, Maxwell’s equations don’t change if you rotate one direction of space into time. > So, Minkowski said, we just combine space with time to a 4 dimensional space-time, and then we can rotate space into time just like we can rotate two directions of space into each other. And that naturally explains why Maxwell’s equations have the symmetry they do have. I have read, enjoyed, and understood a lot of popular physics books. But none of that makes a lick of sense to me. Either I’m dumber than I thought (probably), or I’m not the right audience, or this is a poor explanation.
- datavirtue 4y ago
  The first two paragraphs of that pablum made me leave the post. The author sounded dumb as a rock.
  - antiterra 4y ago
    I’m curious, why did the author sound dumb? What percentage of the population do you think is likely ‘dumb’ by your standards?
- conradev 4y ago
  I enjoyed this book, which had a much more thorough explanation of Minkowski spacetime: https://press.princeton.edu/books/paperback/9780691165714/philosophy-of-physics https://press.princeton.edu/books/paperback/9780691165714/ph... It takes a bit of time with spacetime diagrams to become more familiar with it
skinney6 4y ago
Past and future is a trick our mind plays on us. We collect past and future "moments" and believe them to have reality. As we collect these moments the illusion of a timeline emerges. Notice when your body tenses and or emotions and feelings trigger when you are just having thoughts about the past or the future. Why react to thoughts? The mind uses uncomfortable feelings to keep our attention. To break free you just have to sit with all the feelings and accept. Now is all there is.
- galgot 4y ago
  Yes ! :) shamelessly quoting myself : "My favorite theory about Space and time is the one from Don Hoffman. To summarize, space and time are parts of our interface to interact with other conscious agents , just like our senses of smell, vision, sound. But it is just that, an interface, created by millions years of evolution, and does not shows the true nature of reality, which could be completely incomprehensible to us. Like electricity is incomprehensible to a cat, evolution, which is very power thrifty, provided cats just enough effectives ways to survive and reproduce the way cats do. Same for us. this is very summarized, his ideas goes much farther, for him the base of true reality could be consciousness : https://youtu.be/oadgHhdgRkI https://youtu.be/oadgHhdgRkI and https://youtu.be/ds-7sMfJDUw https://youtu.be/ds-7sMfJDUw "
  - skinney6 4y ago
    I just watched his vid the other day on Big Think; very interesting for sure! I can see how that would apply here too.
- orlp 4y ago
  How do you justify prison sentences for crimes in the past in this framework mental framework?
  - skinney6 4y ago
    We have a memory, but "the past" doesn't exist in it's own right. It's just thoughts and images we are experiencing now, in this moment.
fat_cantor 4y ago
Can't tell whether "Einstein's forth assumption" is a clever simultaneity pun or a typo.
deleted 4y ago
[deleted]
erehweb 4y ago
Related discussion in "1984" [O'Brien to Winston Smith]: 'Is it your opinion, Winston, that the past has real existence?' Again the feeling of helplessness descended upon Winston. His eyes flitted towards the dial. He not only did not know whether 'yes' or 'no' was the answer that would save him from pain; he did not even know which answer he believed to be the true one. O'Brien smiled faintly. 'You are no metaphysician, Winston,' he said. 'Until this moment you had never considered what is meant by existence. I will put it more precisely. Does the past exist concretely, in space? Is there somewhere or other a place, a world of solid objects, where the past is still happening?' 'No.' 'Then where does the past exist, if at all?' 'In records. It is written down.' 'In records. And- ?' 'In the mind. In human memories. 'In memory. Very well, then. We, the Party, control all records, and we control all memories. Then we control the past, do we not?' https://www.abhafoundation.org/assets/books/html/1984/162.html#:~:text='Until%20this%20moment%20you%20had,past%20is%20still%20happening%3F' https://www.abhafoundation.org/assets/books/html/1984/162.ht...

177 points by nsoonhui 4y ago

If somehow humans or human ancestors (AGI?) endure to the point they can bend the laws of physics and play back the light cone, I wonder if they'll be interested in revisiting all of us to learn about the past. To see and touch the dinosaurs, visit Einstein, see everything, even our thoughts. An undetectable time machine that might surround us even now. A traversable field of time. A kind of high fidelity afterlife. (I am clearly not a physicist.)

cercatrova 4y ago
The show Devs actually explores this concept. It's by the director of Ex Machina.
- colordrops 4y ago
  Also Interstellar.
- mdrzn 4y ago
  It was such a good show, with an interesting POV. Wish they would do a 2nd season.
xwdv 4y ago
Personally, I think perhaps we are the machine, right now. Everything that has happened now has already happened, and we’re just reliving it. Who knows what iteration of the loop we might be on right now. Perhaps on our first run free will was much more obvious and abundant, in ways that we simply can’t even imagine right now, kind of like trying to imagine light when you’re born blind. However, the end result still ends up being exactly what you experience now, minus the running dialog of free will. Our body is controlled by our mind, and our mind is controlled by our consciousness, which is capable of observing and altering our mind’s thoughts. But as far as I can tell, we don’t seem to have any mechanism for “observing” our consciousness. That is the missing freewill component, which may have only existed in our first run.
- colordrops 4y ago
  I suspect being able to directly observe consciousness will involve transcending the individual self and end up solving the problem of free will, in that there is no single self to have free will, i.e. consciousness is not tied or confined to any single individual.
  - xwdv 4y ago
    So everything we experience now on an individual level is just the result of that unified consciousness’s choices?
    - colordrops 4y ago
      Assuming that our individual oerception of experience and agency applies analogously to this greater consciousness, then I suppose so, but I don't know if our narrow minds can comprehend or express the way it operates.
- dsego 4y ago
  Simulation theory by Philip K Dick https://youtu.be/bbW6ZOmoFgY https://youtu.be/bbW6ZOmoFgY
- rytill 4y ago
  > But as far as I can tell, we don’t seem to have any mechanism for “observing” our consciousness. That is the missing freewill component, which may have only existed in our first run. Do you think the "first run" version of yourself would have made your HN comment?
  - xwdv 4y ago
    I think somehow the free will of my first run’s version must have willed my consciousness to think about this thought and come to this conclusion.
LeoPanthera 4y ago
Stephen Hawking's time traveller party: https://youtu.be/elah3i_WiFI https://youtu.be/elah3i_WiFI (The invitations were posted after the party had concluded.)
- Geee 4y ago
  Why would anyone show up if they knew that no one will show up?
dalmo3 4y ago
> If somehow humans or human ancestors You probably meant descendants, but that just made your comment delightfully coherent.

thunkle 4y ago

mgdlbp 4y ago
https://en.wikipedia.org/wiki/Information-theoretic_death https://en.wikipedia.org/wiki/Information-theoretic_death ?
- thunkle 4y ago
  Yeah, exactly. How did you come about this?
  - mgdlbp 4y ago
    Not sure; it's not in my notes. I want to say an HN comment, but I don't recognize any of the few that include the link. -- Edit: The browser history still exists, although I cannot disprove that it was created Last Thursday; 'twas the comment near the bottom of this thread that intrigued me with its sole content, that link: https://news.ycombinator.com/item?id=1755748 https://news.ycombinator.com/item?id=1755748
Atiscant 4y ago
If you care about the question more than from a purely curiosity standpoint, there is a difference tween “flesh” and “body” in (at least some) of Christianity. The “Lord of Spirits” (an orthodox podcast) has done an in-depth discussion on both the body of God and the bodies of humans, angels and demons. Just as an example, when Adam and Eve was expelled from the garden they were covered in “garments of flesh/skin” depending on the translation. I do not want to start a discussion on Christianity, just to point to that there is a more subtle understanding in the church whether or not you believe in it.
- FrozenVoid 4y ago
  Body could be 'subtle' astral/etheric matter. Flesh is strictly physical biological matter.

Borrible 4y ago

To answer this question one needs True Detectives. https://www.youtube.com/watch?v=9oX2xFo7JA4 https://www.youtube.com/watch?v=9oX2xFo7JA4 But, ist the other side of the block-universe existing? Is it growing in that direction? Are you on the edge of that growth? Or are you already ghosts of the past talking among themselves? Again. And again. Forever.

dandanua 4y ago

Reminded me of https://twitter.com/DarthPutinKGB/status/1549655121000366080 https://twitter.com/DarthPutinKGB/status/1549655121000366080 "The hard part about doing propaganda is that the past changes so quickly you have no idea what will happen yesterday"

spratzt 4y ago
This is a variation on an old joke. Q: What is the hardest task for a Marxist historian? A: To forecast the past.

pdonis 4y ago

The article does not even discuss the obvious alternative that is perfectly consistent with relativity: all events in your past light cone "exist" (a better term would be "are fixed and certain"). This avoids all of the issues mentioned in the article while not committing you to the "existence" of anything that might not be fixed and certain based on the information you have at any particular time. What always amazes me about discussions like this is how even physicists who are experts in relativity fail to see the obvious implications of the fact that, in relativity, spacetime is divided into three regions instead of two. Instead of just "past" and "future", there are "past light cone", "future light cone", and "spacelike separated". "Past light cone" and "future light cone" behave more or less like our intuitive concepts of "past" and "future"--the past light cone is what is fixed and certain and can't be changed, and the future light cone is what can possibly be changed based on things we do here and now. But the spacelike separated region is not like anything in our intuitions, since it is not fixed and certain as far as we know here and now, but we also can't do anything here and now to change it. But instead of recognizing all this and considering its implications, discussions like this article talk as if the only way to divide spacetime up into regions is "past" and "future" separated by a "now" slice (and the "now" slice is of course frame-dependent so it can't have any physical meaning), or to talk as if the only thing that "exists" is the single point in spacetime that is our "here and now". It's disappointing.

panda-giddiness 4y ago
The author hasn't neglected to consider light cones – she literally describes them in her post, as evinced by her mentioning 45 deg lines on a spacetime diagram, causally connected/disconnected events, etc. Of course you have described a perfectly good way of thinking about the past/future (and to your credit, she surely should've included what you described). But in her defense, what you have described is also the most obvious explanation consistent with special relativity – the "past" and "future" outside one's line cone cannot be objectively defined, as you could always (hypothetically) boost to another frame in which the disconnected past becomes the disconnected future (and vice versa). Undoubtedly the author is aware of this fact, so I assume the purpose of this blog post was simply to motivate other hypotheses about the nature of time.

bni 4y ago

My favorite Sci-Fi about this: https://www.goodreads.com/book/show/823062.The_Light_of_Other_Days https://www.goodreads.com/book/show/823062.The_Light_of_Othe...

Brajeshwar 4y ago

OffTopic but curious (not derogatory): Of late, I feel that her video are deepfake with Sabine Hossenfelder speaking from behind. I subscribe to her YouTube channel and I'm a regular. What am I missing?

djmips 4y ago
I can see why you think that but I don't think it's quite so elaborate. More likely just production changes, maybe filters.
rubslopes 4y ago
It's the first time I've seen a video of her and I had the same impression. I think it has something to do with her lack of arm movement (also not derogatory).
ubercore 4y ago
There's a smoothing filter on that video that makes it look a bit fake.
rapjr9 4y ago
She uses green screen a lot to add all the graphics behind and to the sides, which often makes the edge of the person a little random (pixels blink on and off), and the shadows in the graphics may not fall in the same direction as the shadows created by the light on her. In a similar way weather on the news makes the weather person look a bit surreal.

bowsamic 4y ago

Interesting article. Not entirely relevant, but I think that the Buddhist view of time is interesting, and I guess quite relevant to this block universe idea. In the Buddhist view, all things are "emptiness", shunyata, without self-existence. This means that there is no fundamental basis with which you can distinguish between things. For example, there is no fundamental property that you can use to distinguish between you and I, or an apple and a keyboard, or even your body and your consciousness. The distinctions are just concepts that we make up and assert that the world fits into it. The Heart sutra says that not only is this true for all the elements that make up our experience, but even also for causal connections such as time. This view of time was most explicitly emphasised by the Soto Zen philosopher Dogen. He called it Uji, which means "time-being". Effectively he said that being equals time, and that really all time is right now: [quote] An ancient buddha said: For the time being stand on top of the highest peak. For the time being proceed along the bottom of the deepest ocean. For the time being three heads and eight arms. For the time being an eight- or sixteen-foot body. For the time being a staff or whisk. For the time being a pillar or lantern. For the time being the sons of Zhang and Li. For the time being the earth and sky. "For the time being" here means time itself is being, and all being is time. A golden sixteen-foot body is time; because it is time, there is the radiant illumination of time. Study it as the twelve hours of the present."Three heads and eight arms" is time; because it is time, it is not separate from the twelve hours of the present. [/quote] (https://www.thezensite.com/ZenTeachings/Dogen_Teachings/Uji_Welch.htm https://www.thezensite.com/ZenTeachings/Dogen_Teachings/Uji_...) The way we understand this as Buddhists, is that we are both at the very beginning and very end of our path, at the same time we are both deluded beings and also perfectly enlightened Buddhas: > Time is not separate from you, and as you are present, time does not go away. As time is not marked by coming and going, the moment you climbed the mountains [walked the Buddhist path] is the time-being right now. So effectively, we believe that all moments are contained in this moment, because there is no fundamental basis by which we can say that any other moment is separated from this moment. Before and after are illusions, they are just ideas that we have right now.

ncmncm 4y ago
"between you and me".

djmips 4y ago

I'm more in the emergent time camp. But the point is that it isn't an open and shut case with regard to the block universe.

amriksohata 4y ago

Somewhat related. In the Srimad Bhagvatam Canto 5, a Hindu scripture, it states that the Universe shell (known as the Brahmanda shell) contains all past, present and future events. https://www.facebook.com/VedicCosmology/posts/do-the-past-and-future-exist-a-new-theory-claims-that-time-does-not-move-forward/1608277619480164/ https://www.facebook.com/VedicCosmology/posts/do-the-past-an... https://gauragopala.blogspot.com/2019/02/we-are-deep-inside-larger-universe-made.html?m=0 https://gauragopala.blogspot.com/2019/02/we-are-deep-inside-...

bambax 4y ago

I'm not sure I understand any of this, but I'm trying. Can this be summarized as "for any two points in time, one can always find an observer for whom those two points are simultaneous"?

dandanua 4y ago
For any two points in the event space (spacetime), which are causally disconnected (space-like separated, which means one point is not in the light cone of the other), there is always an observer that perceives them simultaneously. There are also observers for which one point precedes the other and vice versa. There are observers that can't see (or cause) one of the points, or both.
- bambax 4y ago
  Ah, but then it's not especially counterintuitive: causally independent events can happen in any order... The layman's notion of "time" implies causality/irreversibility. Events that have no causal relation between all have their own little timeline, and it's not troubling or surprising to consider that they are simultaneous / that we examine them in a kind of superposition. Or am I saying something stupid? ;-)
  - dandanua 4y ago
    That's right. We've just learned to believe that there is only a past and a future, where the future is caused by the past. In Special Relativity those are just two light cones, but there are always other events. Though, in a flat spacetime they will affect our future, eventually, because we are moving slower than light. In other words, every event is past to some of our future event. The Big Bang is a different story, because the theory says that spacetime is evolving.

fbn79 4y ago

I suggest you the book "Order of time" by Carlo Rovelli. One think I learned by the book is the locality of time. For example imagine one day people living on mars and you wonder what that people doing in this moment. Well is a wrong question. There is no such thing "this moment" in two far placeces

ffwd 4y ago

I feel like I must be missing something but in the part about the relativity of simultaneity [0] I feel like this is more about the relativity of the observers and the limitations of speed of light than it is about the ontology of time itself? The definition of "now" as when the light hits the mirror on each side is a "constructed" now, a false now if you may. It takes the light longer on the right side than the left side because she is moving through space, all that tells me is that there is no way to communicate a "now" between different observers because there can't be instantaneous communication between observers, not that time itself is relative or physical stuff itself doesn't have a constant time? She says in the video that we have to find a way to operationalize how to find a now, to measure it empirically but maybe that's not possible without running a complete simulation after the fact. But to me it seems not surprising that without instantaneous communication there is no way to create a "now" empirically but that doesn't mean it extends to the ontology of physical stuff itself or time itself. There would still be a time in there (you should be able to see it in a simulation?) Also for example, if you use sound instead of light, if I'm far away from a sound source (farther than the speed of sound), and another observer is closer to it, we would not be able to use the sound source as a source "now", because I would hear it later. Is this the same type of situation or different? I feel like I must be missing something fundamental here but I'm sort of going out on a limb so please don't slaughter me :P [0] https://youtu.be/GwzN5YwMzv0?t=542 https://youtu.be/GwzN5YwMzv0?t=542

platz 4y ago
Are you not just taking the position that the only things that exist have to be both 1) Now and 2) Here
- ffwd 4y ago
  I suppose so... Not sure about the second part but for the first part I think that comes from the idea that I don't think we've ever empirically or even subjectively observed the universe in any other state than "now". We've never personally nor in a scientific experiment observed any physical system being in more than one state, and that one state has to by definiton be in the "now" (Unless I am mistaken). So the past and the future states are essentially nowhere to be found in empiricism ? As for the "here" part I am not sure how to respond to that but it sounds right - any observer has to have contact in some direct way (whether with a scientific instrument or not) to the thing physical system he is observing and as such claiming anything about anything indirect or far away is very hard if not impossible so you get the "here".

galgot 4y ago

My favorite theory about Space and time is the one from Don Hoffman. To summarize, space and time are parts of our interface to interact with other conscious agents , just like our senses of smell, vision, sound. But it is just that, an interface, created by millions years of evolution, and does not shows the true nature of reality, which could be completely incomprehensible to us. Like electricity is incomprehensible to a cat, evolution, which is very power thrifty, provided cats just enough effectives ways to survive and reproduce the way cats do. Same for us. this is very summarized, his ideas goes much farther, for him the base of true reality could be consciousness : https://youtu.be/oadgHhdgRkI https://youtu.be/oadgHhdgRkI and https://youtu.be/ds-7sMfJDUw https://youtu.be/ds-7sMfJDUw

Trasmatta 4y ago
How does he reconcile space and time being just an interface created by evolution, when evolution itself is a process that only happens because of time?
- galgot 4y ago
  Well, evolution happening because of time is again how we "understand" it because we have no other ways to. He doesn't say he has the answer to the true nature of time and space, he is a searcher. Check the vids, it is much better explained than I can do :)

adriand 4y ago

I’m not sure who the intended audience of this upcoming book is, but if it is laypeople, I feel as though the level of explanation is too advanced. Eg: > Just like a ball doesn’t change if you rotate one direction of space into another, Maxwell’s equations don’t change if you rotate one direction of space into time. > So, Minkowski said, we just combine space with time to a 4 dimensional space-time, and then we can rotate space into time just like we can rotate two directions of space into each other. And that naturally explains why Maxwell’s equations have the symmetry they do have. I have read, enjoyed, and understood a lot of popular physics books. But none of that makes a lick of sense to me. Either I’m dumber than I thought (probably), or I’m not the right audience, or this is a poor explanation.

datavirtue 4y ago
The first two paragraphs of that pablum made me leave the post. The author sounded dumb as a rock.
- antiterra 4y ago
  I’m curious, why did the author sound dumb? What percentage of the population do you think is likely ‘dumb’ by your standards?
conradev 4y ago
I enjoyed this book, which had a much more thorough explanation of Minkowski spacetime: https://press.princeton.edu/books/paperback/9780691165714/philosophy-of-physics https://press.princeton.edu/books/paperback/9780691165714/ph... It takes a bit of time with spacetime diagrams to become more familiar with it

skinney6 4y ago

Past and future is a trick our mind plays on us. We collect past and future "moments" and believe them to have reality. As we collect these moments the illusion of a timeline emerges. Notice when your body tenses and or emotions and feelings trigger when you are just having thoughts about the past or the future. Why react to thoughts? The mind uses uncomfortable feelings to keep our attention. To break free you just have to sit with all the feelings and accept. Now is all there is.

galgot 4y ago
Yes ! :) shamelessly quoting myself : "My favorite theory about Space and time is the one from Don Hoffman. To summarize, space and time are parts of our interface to interact with other conscious agents , just like our senses of smell, vision, sound. But it is just that, an interface, created by millions years of evolution, and does not shows the true nature of reality, which could be completely incomprehensible to us. Like electricity is incomprehensible to a cat, evolution, which is very power thrifty, provided cats just enough effectives ways to survive and reproduce the way cats do. Same for us. this is very summarized, his ideas goes much farther, for him the base of true reality could be consciousness : https://youtu.be/oadgHhdgRkI https://youtu.be/oadgHhdgRkI and https://youtu.be/ds-7sMfJDUw https://youtu.be/ds-7sMfJDUw "
- skinney6 4y ago
  I just watched his vid the other day on Big Think; very interesting for sure! I can see how that would apply here too.
orlp 4y ago
How do you justify prison sentences for crimes in the past in this framework mental framework?
- skinney6 4y ago
  We have a memory, but "the past" doesn't exist in it's own right. It's just thoughts and images we are experiencing now, in this moment.

fat_cantor 4y ago

Can't tell whether "Einstein's forth assumption" is a clever simultaneity pun or a typo.

deleted 4y ago

[deleted]

erehweb 4y ago

Related discussion in "1984" [O'Brien to Winston Smith]: 'Is it your opinion, Winston, that the past has real existence?' Again the feeling of helplessness descended upon Winston. His eyes flitted towards the dial. He not only did not know whether 'yes' or 'no' was the answer that would save him from pain; he did not even know which answer he believed to be the true one. O'Brien smiled faintly. 'You are no metaphysician, Winston,' he said. 'Until this moment you had never considered what is meant by existence. I will put it more precisely. Does the past exist concretely, in space? Is there somewhere or other a place, a world of solid objects, where the past is still happening?' 'No.' 'Then where does the past exist, if at all?' 'In records. It is written down.' 'In records. And- ?' 'In the mind. In human memories. 'In memory. Very well, then. We, the Party, control all records, and we control all memories. Then we control the past, do we not?' https://www.abhafoundation.org/assets/books/html/1984/162.html#:~:text='Until%20this%20moment%20you%20had,past%20is%20still%20happening%3F' https://www.abhafoundation.org/assets/books/html/1984/162.ht...